Microstructures and mechanical properties of FeCoCrNi-Mo High entropy alloys prepared by spark plasma sintering and vacuum hot-pressed sintering

Abstract

Fully dense FeCoCrNi-Mo high entropy alloy (HEA) was successfully prepared by two different sintering methods: spark plasma sintering (SPS) and vacuum hot-pressed sintering (VHP). The microstructures and mechanical properties of HEA prepared by both methods were systematically investigated and compared. The HEA powders were uniformly distributed at approximately 10 μm after 20 h of ball milling. The SPS sample maintained a single FCC structure and Multiple microstructures of σ phase, Mo2C and Cr23C6 carbides precipitated in the VHP samples. As a result of the precipitation of these hard and brittle phases, the VHP samples exhibited superior hardness and wear resistance but a lower flexural strength and toughness relative to the SPS samples. Considering the different microstructures and mechanical properties between SPS and VHP samples, the sintering method should be selected according to the specific working conditions, and the SPS process has potential in realizing rapid low-temperature sintering for HEAs compared with other sintering methods.